Polycarbonate is a popular material for making ophthalmic lenses. Polycarbonate lenses are often produced by injection and compression molding of liquid resin. The conventional operation causes the lenses to remain with residual stress effects.
These residual stress effects can affect the dimensional stability of the lenses, and lead to other problems. For example, overly-stressed polycarbonate lenses can warp upon storage or wear. The edges of such lenses can have varied optical powers. A phenomena known as cold creep can also cause problems in the lenses.